1. Field of the Invention
This invention relates to a method for rolling a material while guiding the whole of the rolled material from its leading end to its tail end to a caliber of rolling rolls by use of a roller guide disposed in a train of rolling mills for continuously rolling the material into section steel, bar steel, wire rod or the like.
2. Description of the Prior Art
There have been so far proposed rolling methods for increasing the accuracy of the outside size of a rolled material by providing a roller guide with a sensor or the like, as described hereinafter.
The rolling method using a roller entry guide disclosed in U.S. Pat. No. 4,790,164 adopts measuring means such as a pressure sensor to measure the stress of guide rollers suffered from the rolled material. In the conventional rolling method, the force of the rolled material exerted to the guide rollers is maintained constant on the basis of the results obtained from the measurement in order to compensate wear on the guide rollers and the front-stage rolling roll, and the axis of the roller entry guide is exactly aligned with a pass line to achieve high accuracy of the outside size of the rolled material.
There is disposed a pass line adjusting method for entry guide in Japanese Patent Application Publication No. HEI 07-275916(A). In this conventional method, after guiding a rolled material to a rolling mill by use of a roller guide disposed at the entrance of the rolling mill, the outside size of the stock rolled by the rolling mill is measured at the exit of the rolling mill to detect the dislocation of the roller guide relative to the pass line from the measured results, so that the axis of the roller entry guide is exactly aligned with a pass line to achieve the accuracy of the outside size of the rolled material.
The former rolling method described above makes it possible to ascertain whether the rolled material embraced by the guide rollers becomes thicker or thinner compared with a material having a standard outside size on the basis of values detected from sensors disposed on either side of the guide rollers for detecting the force of the rolled material exerted on the guide rollers. However, this conventional method involves a problem to be solved such that the gap between the guide rollers and embracing force of the guide rollers cannot be changed with a material to be rolled during a rolling process. Consequently, this conventional method entails such a disadvantage that the gap between the guide rollers cannot be finely adjusted even when it is slightly wide or narrow and required to be adjusted.
The latter rolling method enables the alignment of the roller guide with the pass line to be effected so as to bring the shape of the rolled material close to the desired shape while measuring the outside size of the roller material. This conventional method should be improved so as to produce a rolled material with high dimensional accuracy by regulating the gap between the guide rollers and embracing force of the guide rollers.